CSC B1.4

• Algorithm is sequence of well-defined steps to solve a problem/sequence of steps arranged in a specific logical order which produces a solution for a problem
• Good algorithm requirement:

  1. Input
  2. Output
  3. Generality
  4. Correctness
  5. Finiteness
• INPUT is conceivable that an algorithm may have no input. However, such algorithms are trivial and quite rare
• OUTPUT is an algorithm that does not produce anything is worthless
• GENERALITY is it must be general (can be used for different inputs)
• CORRECTNESS is It must be correct and must solve the problem for which it is designed
• FINITENESS is it must execute its step and terminate in finite time
• to represent algorithm:

  1. IPO Chart
  2. Pseudocode
  3. Flowchart
• Find the square of a number INPUT : Number

  PROCESS : Calculate Square

  OUTPUT: Square
• Calculate and display the average of three marks INPUT: mark1, mark2, mark3 PROCESS: calculate average OUTPUT: average
• Calculate the area of a circle INPUT: radius

  PROCESS: calculate AreaCircle

  OUTPUT: AreaCircle
• RM200 per night, service charge is 15%, determine total amount:

  INPUT: Number_Of_Night PROCESS: Calculate Total_Payment

  OUTPUT: Total_Payment
• PSEUDOCODE is written statement of an algorithm using a semiformal language with limited vocabulary
• The main purpose of using pseudocode is to define the procedural logic of an algorithm in a simple, easy-to-understand for its readers, who may not be proficient in computer programming language
• In order to succeed in accomplishing its objectives, a pseudocode must: 1. Have limited vocabulary 2. Easy to learn 3. Produce simple, English-like narrative notation 4. Capable of describing all algorithms, regardless of their complexity
• General format for pseudocode: START DECLARE Variable1, Variable2,..... INPUT/READ/ENTER/GET....(input) Formula/Condition.... (process) OUTPUT/DISPLAY/PRINT....(output) END
• PROBLEM STATEMENT 1: Find the square of a number

  START DECLARE Number, Square

  INPUT Number

  Square Number×Number

  PRINT Square

  END
• Calculate and display the average of three marks

  START DECLARE Mark1, Mark2, Mark3, Average INPUT Mark1, Mark2, Mark3 Average (Mark1 + Mark2 + Mark3)/3 PRINT Average END
• Calculate the area of a circle

  START DECLARE Radius, AreaCircle

  INPUT Radius

  AreaCircle = 3.142×Radius×Radius

  PRINT AreaCircle

  END
• RM200 per night, charge is 15%, total amount

  START DECLARE Number_Of_Night, Total_Payment, Total INPUT Number_Of_Night Total = Number_Of_Night×200 Total_Payment = Total+(0.15×Total) PRINT Total_Payment

  END
• Flowchart is a set of standard shaped boxes that are connected by flowlines to represent an algorithm